tailieunhanh - Integrated Assessment of Health and Sustainability of Agroecosystems - Chapter 7

Trong một sức khỏe sinh thái nông nghiệp và đánh giá tính bền vững, các chỉ số nên được phân tích theo hai cách: (1) như các biện pháp của sức khỏe tổng quát tại một điểm trong thời gian và (2) như dự báo về tính bền vững lâu dài của nó (Costanza et al, 1998) và sức khỏe. Đánh giá tình trạng sức khỏe của một sinh thái nông nghiệp liên quan đến việc so sánh và tương phản một loạt các phép đo chỉ số chống lại một tập hợp các cắt và các giá trị ngưỡng. | 7 An Assessment of Health and Sustainability of a Smallholder-Dominated Tropical Highlands Ecosystem INTRODUCTION In an agroecosystem health and sustainability assessment indicators should be analyzed in two ways 1 as measures of overall health at a point in time and 2 as predictors of its long-term sustainability Costanza et al. 1998 and health. Assessing the health status of an agroecosystem involves comparing and contrasting a series of indicator measurements against a set of cutoff and threshold values Canadian Council of Ministers of the Environment 1996 based on the goals and objectives of the agroecosystem. A suite of indicators would in most cases contain several dozen variables. A method of summarizing and presenting such data must preserve its holistic and multidimensional nature while providing meaningful quantitative and easily understood criteria for evaluating agroecosystem health. One approach is to combine indicators into indices such as total factor productivity Ehui and Spencer 1993 ecosystem health index Costanza 1992 and agricultural sustainability index Nambiar et al. 2001 . A fatal disadvantage of this approach is that indices place weights on different indicators without providing a rational basis for their the weights choice. Another disadvantage is that these indices would eventually require some form of decomposition to provide managerially useful information a decomposition that more often involves a reassessment of the initial suite of indicators used to compute the index and back to the initial problem of how to summarize information from indicators. Less unencumbered by the latter but still crippled by the weighting problem are approaches such as ecological footprint Wackernagel and Rees 1997 and the method proposed by Afgan et al. 2000 based on decision support systems and the general indices method. A systems approach to evaluating indicator data requires an understanding of how agroecosystem goals and values are seen to relate .